Automatic synchronizer



1932- P. M. STIVENDER AUTOMATIC SYNCHRONIZER Filed Dec. 5, 1929 l l l l l f as Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE PAUL M. STIVENDEB, OF -WEST ALLIS, WISCONSIN, ASSIGNOR TO ALLIS-CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE AUTOMATIC SYNCHRONIZER Application filed December 5, 1929. Serial No. 411,947.

This' invention relates to automatic synchronizers.

One of the objects of the invention is the provision of means which will connect two al ternating current sources when they have the same frequency and are in phase. Another object is the provision of means in which the connection of the two sources is made dependent upon the time rate of chan e of the phase angle between said sources. nother object is the provision of means in which the connection of the two sources is made dependent on the time rate of change of relative frequency as between said sources.

Still another object is to provide a synchronizer in which the chances for the connection of the sources is increased, and more particularly, in cases where the time rate of change of phase angle remains small for but a short time, thereby shortening the time it takes for the sources to beconnected after the control has been initiated.

It is also an object to provide a synchronizer in which the chances that the sources will be connected when they are out of phase are minimized.

A further object is the provision in a means for connecting two sources when they have the same frequency and phase of a means which will prevent the reconnection of said sources when the connecting means has been opened. if said sources are out of phase.

A still further object is to minimize the effect on the time of connection of the sources with regard to their frequency and phase relations, of the maximum voltage of the line or generator electromotive forces or both. It is also an object to provide a synchronizer in which a predetermined inequality in the electromotive forces of the sources when they are substantially in phase will prevent the connection of the sources. Other objects will appear hereinafter as the description of the invention proceeds.

The novel features of the invention will appear from this specification and the accompanying drawing forming a part thereof showing one embodiment of the invention, and all thesenovel features are intended to be pointed out in the claims.

In the drawing:

Fig. 1 is a diagrammatic showing of one embodiment of the invention.

Figs. 2 and 3 are views of details; and

Fig. 4 is adiagram of certain electromotive forces and time relations relating to the mode of operation of the invention.

In this specification the terms alternating current and electromotive force will be abbreviated to A. O. and E. M. F. respective- Referring to Fig. 1, an A. C. generator 1 is shown connected to conductors 2 which may be connected by means of a circuit breaker 3 to an A. (J. line 4. The line 4 leads to another source or sources of A. C., not shown. The circuit breaker 3 is provided with an operating coil 5 whereby the circuit breaker may be closed. In the closed position the circuit breaker is here shown as held by a latch 6 which may be tripped by a trip coil 7. The trip coil 7 may be energized in response to any desired condition. y

Across two of the conductors 2 leading from the generator is connected a transformer 8, and across the corresponding conductors of the line 4 is connected a trans former 9. One of the terminals of the secondary of transformer 8 is connected to a control bus 10, the other terminal being connected to a conductor 11 which is connected to a tap 13 on the secondary of transformer 9. One of the terminals of the secondary of transformer 9 is connected to a control bus 12. The connections of transformers 8 and 9 to the buses 10, 12 is such that when the generator and line are in phase the E. M. F. across these buses will be zero.

A relay 14 is here shown as having contacts 15 and 16 interposed in the control buses 12 and 10, respectively. The relay 14 may have oneterininal connected to control bus 10 at the left of contact 16, the other terminal being connectible through a switch 41 and an auxiliary switch 42 to the conductor 11. The auxiliary switch 42 is closed when the circuit breaker 3 is open and is adapted to open when the circuit breaker has been operated to closed and latched position, there being a lost motion connection between the circuit breaker operating means and the switch 42, as indicated. The switch 41 may be operated in any suitable fashion so that it is closed only when it is desired to synchronize the generator and the line.

Leading from the conductor 11 is a conductor 17 between which and control bus 12 a motor 18 is connected. This motoris thus "of relay 36'as here fed from transformer 9. Connected between the, cnductor'171and the control bus .is

another motor 19, this motor being thus fed from transformer 8. The motorsjl8 and 19 maybe synchronous motors or synchronous induction motors, or, generally, motors the speed of which will vary synchronously with the frequency of the line. and generator respectively. The motor 18 has an insulating disk 20 mounted .on the shaft thereof. The disk 20 a-s shown in F ig. 2 is provided with a plurality of contacts 21, 22,23 and 24 which are flush with'the face of the disk and are all connected electricallyto a slip ring 27 Facing. the disk 20 is another disk 25 which is here shown asmounted on the shaft of motor 19. The disk 25 carries a contact 26 which projects'slightly from the .face of the disk 25 toward the face of disk 20, and is adapted to'imake contact with one or the other of the contacts on disk 0. The contact 26 is electrically connected to a slip ring28.

A relay 29 is here shown as having one terminal connected to control bus 10, the other terminal being connectible'through a resistance 30,- a conductor39, a resistance 31 a conductor 32, to the other terminal of the secondary of transformer 9. In conductor 39 is interposed a contact 38 controlled by an adjustabletimejlimitrelay 36. Also interposed in conductor 39 are the slip rings 27 and 28and the contact 26, e Relay 36 is connected across the control buses'lO, 12 through a resistance 37. It will however be noted that one of the terminals shown is connected to control bus 10 tothe right of contact 16 whereas the other terminal is connected to the control bus12 to the left of contact 15.

for a purpose to be hereinafter set forth. Therelay 36 is of any suitable form such that when its operating coil has an E. M. F. less than a predetermined value applied theretothe contact 38 will begin to move toward the closed position and will complete the closing movement in a predetermined adjustable time.

I The relay 29 is provided with two contacts 33,34, the contact 33being adapted to complete a conducting path which is connected so'as to short-circuit the contacts 38 and any The operation is as contact'made by'the contact 26. 33 thus, when closed, serves as a maintaining contact for relay29." The contact 34 is here shown as adapted to close thecircuit of coil 5 through a s'ourcef here shown'as a battery 35. fOllQws. Let it be The contact poles is chosen,

of convenience;

assumed that switch 41 is closed and that revay 14 is therefore energized thereby closing contacts 15, 16 and energizing control buses 1O, 12. The motors 18, 19 arenow operating, the disks 20 and 25 rotating at speeds in accordance with the line and generator frequency respectively; If the generator fre= quency is not equal to that of the line there will berelative motion between the disks 20 and 25 and consequently the contact 26 will periodically engage the contacts 21, 22,23 and 24. The generator and line willrbeintphase when contact 26 is in tacts 21 or 23, for example, and will be 180 degrees out of phase when contact 26 engages contact 22 or 24, for example. M This is the case where the motors 18 and 19 are ofjthe four-pole type. Where some othernuinber of the number of contacts on the disk 20 will be changed accordingly'as .w'ill be apparent to those skilled in the art." The relay 36 will be effectively energized'when ever the E. M. F. across buses 10, 12 is higher thana predetermined value as determined by the relay itself or the adjustment of resist ance 37, or both.- l/Vhen th'elE. across buses 10,12 decreases to" a predetermined value the relay 36 will be no lon 'erableto maintainthe contact 38 open andtliis contact consequently bjegins'to move toward the closed position, being retarded in this'motion by any suitable means, this being here diagram maticallyindicated as a dash potforj thesake Sincethe transformers 8 and 9 are connected I line and'generator are in phase there is no E. M. F. across relay36, the contact 38will begin to close whenever the generatorjand line are approaching the in-phase relation and will be held open whenth'e line and genof phase by a predetermined It will therefore be .apparentthat the to relay36 so thatwhen the.

engagement with con- The variation of E. M. F. acrossrelay 36 is 2 shown diagrammatically in Fig. 4, the ordi nates of the curve representing the effectiveor root meansquare values of ll/IIF, and. the

abscissae representing time The magrimurn E. M. F. impressed upon relay 36 is'jhere represented as the ordinate Assuming that the generator frequency is changing and a p proaching that of the line the generator. and

line will at'first rapidly phase and out-of-phase less. and less rapidly quency becomes nearly go [through the inrelations andthen a t e e a o fif a of h in T e voltageacross relay- 36 willtherefore vary in a the manner as represented bythe loops 43,44, i e- T nslo p43 a a exa' pla the line and enerator are in hase where the loopcrosses the ti ineaxis and are degrees out of phase at the top iofthejloop. I Thus width of the base of the loop alsii represents a change of 360 degrees in phase angle, and as the line and generator frequency approach each other the bases of the loops become longer. Stated in other words, the time rate of change of the phase angle between the generator and line becomes smaller and smaller as the generator frequency is approaching that of the line. Clearly, this time rate of change of phase angle also depends upon the time rate of change of frequency.

If as previously assumed the generator and line are in phase when contact 26 is in engagement with contact 21 the time during which this engagement is maintained will be very brief if the time rate of change of phase angle is large. This is represented in Fig. 4 by the time 53. As the time rate of change of phase angle becomes smaller the time during which contact is made by contact 26 when the generator and line are in phase will become longer as represented by the times 54, 55. It will be understood however that the contacts on the disks and are small so that little relative motion between the disks 25 and 20 is necessary to interrupt the contact. While contact is also made between contact 26 and contacts 22, 24, for example, when the generator and line are 180 degrees out of phase, it will be apparent that relay 29 will not be then energized because contact 38 is held open at that time.

As previously stated the relay 36 is effectively deenergized when the voltage across said relay reaches a predetermined minimum. If a horizontal line is drawn through the loops 43, 44, at a height E above the time axis it will cut the loop 43 1n, for example, the point 46. If the heightE is taken as the hereinbefore mentioned minimum'E. M. F- the contact 38 will begin to close when the E. M. F. across relay 36 reaches the point 46 on loop 43. At this time the generator and line are 0: degrees out of phase and will be in phase in a time 49. The contact 38 closes after a time 52. It will be noted that the end of this period of time falls after the end of the period of time 53 during which contact 26 is in engagement with contact 21, for example. Thus, the time rate of change of phase angle is too rapid so that it would be inadvisable to connect the generator to'the line at this time. The E. M. F. across relay 36 then increases again along 100 44 thereby opening contact 38 when the E. F. increases above the line whose ordinate is E When the E. M. F. again decreases to the value E at point 47, contact 38 again begins to close but, as in the case hereinbefore mentioned, at the time the contact 38 closes, contact at 26 has already been broken as represented by the time 54. When howeverthe time rate of changeof phase angle is small enough as represented. by loop 45, or by the number of degrees a divided by time 51, the contact 38 begins to close at point 48 and closes at the end of period 52. At this time contact is also being made at 26 as represented by the time 55. Since contacts 26 and 38 are contemporaneously closed relay 29 will be energized and contact 33 will maintain said relay energized as hereinbefore set forth. The closing of contact 34 of relay 29 energizes the coil 5 of circuit breaker 3 thereby connecting the generator to the line. The closing of the circuit breaker opens auxiliary contact 42 thereby deenergizing the relay 14 and disconnecting motors 18 and 19. 7

It will be noted that while after the opening of relay 14 the relay 36 is no longer supplied by transformers 8 and 9 in opposition, there is a leak circuit for this relay extending from conductor 12 through said relay and resistance 37 through conductor 10, motor 19, conductor 17, conductor 11 to the tap 13. The current flowing through this leak circuit is sufiicient to maintain contact 38 open. This is for the purpose of preventing the immediate reclosure of circuit breaker 3 in case the same is tripped out, on overload for example, should the contact 26, when the motors l8 and 19 stop, he in engagement with one of the contacts on disk 20. It will be evident, under such condition, that if contact 38 were in engagement at the time circuit breaker 3 opened, the relay 29 would be at once energized thereby immediately reclosing the circuit breaker, and this would occur possibly at a time when the generator and line were out of phase, since the synchronizer would not have had an opportunity to properly control relay 29.

It will be noted that the connection of relay 29 is such that the upper half of the secondary of transformer 9 and the secondary of transformer 8 are in opposition when the line and generator are 180 degrees out of phase. This prevents improper closure of the circuit breaker if contact 38 should be closed by some accident to the circuit of relay 36, for example, the contact 38 being then closed when the sources are out of phase.

In the foregoing explanation of the operation in connection with Fig. 4, it has been assumed that the E. M. F.s of the line and generator are equal or substantially equal. It will be apparent that if they are not equal the E. M. F. across relay 36 will not fall to zero. Thus, referring to 4, this means that the loops 43 etc. will not reach the time axis. Considering loop 45, for example, if such a loop does not reach the time axis the line representing the E. M. F. E will cut the right hand .or descending side of the loop later in point of time and therefore the time 52 may end at a time when the period of contact 55 has already ended, it the difference in E. M. F. is more than a predetermined amountaTherefore thescircuit breaker will not be closed under these conditions.

, It will he'apparent, in-.general,.that since ture is of particular value in getting the generator on the line fast, since there are more times when the tune rate of change of phase angle isslow for a short period of b11118" (or for a small changein phase, say degrees) period (or for a large change than-for a long Moreover,in prior in phase,.say degrees) svstems in which the chan e in Qh'ase angle is e c r l to almost 90 degrees from the time that a given relay'acts untilit closes its circuit, the time rate of change may be the proper'slowrate at the beginning of this change and a faster and improper rate at the end of the change, thereby resulting in improper and unsafe connection ofthe generator to the line: Such con-' ditions occur in certain typesof water wheels the speed of which is somewhat unstable at no load. V r

Referringagainto Fig. hit will be apparent that itthemaximum EMF. E is higher or lower (within the usuallimitsof fluctuation, of line and generator Ell 1F.) this will *not materially change the angle at which the Therefore the in loops meet the time axis.

on the time fluence of the maximum value E of closure of relay 36 is small.

It should be understood that it is not. desired to limit the invention to the exact details of construction shown and described, for obvious modifications may occur to per sons skilled in the art.

It is claimed and desired to secure by Let-V tersPatent:

1. In a means responsive to the phase relations of two A. C. sources, two transformers each energized from one of said sources, a control circuit, a contactin said control circuit, means'for causing said contacts-to close upon occurence of eXac-t'equality of phase between said sources, a second contact in said control circuit, and means serially connected to said't-ranstormers for holding said second contact open as long as the'vector sum o-t'the EMQ F.s across corresponding pairs of con ductors of said sources is above a-predeten' mined amount.

v 2. In a means responsive to the phase rela-' tions of two A. C. sources,-two transformers respectively energized from said sources, a control circuit, motor driven contactsoperas .atilve to energize said controlicircuit respon sive to equallty of phase between said sources,

has-fallen below said predetermined amount. 3

3. In a meansresponsive to the phase'and frequency relations ofrtwo A; (l-sourcs, a

switch, a circuit for controlling said switch,

contacts: in said and 18O electrical degrees'outof phase, said contacts being closed and openedperiodically.

when said sources areof different frequencies, other contacts 1n said-control circuit, means said sources for eliecting a closurerofsaid other contacts only when saidvector sum is below apredeterminedamount, and means for retarding the closure sponsive means. i 4. In combination, two A. C(sources, a cir? cuit breaker interposed between saidsources, a pair of'transform'ers connectedacross said sources respectively, g

operable motors connected to said transformers respectively, a pair of contacts rotatable in substantially parallel planes by said /motorsrespectively, said contacts being disposed tocome' into engagement when said means for so feedingsaid relay fromsaid transformersthat when said sourcesareain phase said'relay will be deen'ergized, and means including a circuit contact and said pair of contacts are interposed for causing closure of said circuit breaker onlyiwhen said pair of contacts come into engagement after said relay'has been deenergized for a predetermined time;

5. In combination, two A. C. sources,'a circuit breaker interposed between-said sources, a pair-of transformersconnected across said sources respectively, a pair ofsyn chro-nously operable motors connected to said transformers respectively, rotatable in substantially said'motors at the speed of said motors respectivly,nsaid 'conta cts being disposed to come into engagement when said-sources are in phase, a relay havinga contact and hava pair of contacts mg an operating winding so serially connected with said transformers that when said sources are in phase the E. M. F; across said operating. winding will be substantially zero,

means comprising a retarding device for causing said relay'contactto move to .its closed position saidoperating fore'said rotatable contactscome into; engageoi Said re- A i a pair ofsynchronously in which'said relay parallel planes bybeiore the; E. M. 'F. across winding reaches zero, and be-.

V circuit, means for closing said contacts when SllCl sources'are-m phase 1 03 sourcesare inphase, a relay having a contact,-

ment, and means including a circuit in which said relay contact and said pair of contact-s are interposed for causing closure of said circuit breaker.

6. In combination, two A. C. sources, a circuit breaker interposed between said sources, means for closing a contact when said sources are in phase, a second means for closing a second contact when said sources are in phase, means controlled iointly by said contacts for closing said circuit breaker, means including a relay for supplying the two means controlling said contacts with current from both of said sources, means whereby opening of said circuit breaker energizes said relay, and means whereby one of said means controlling one of said contacts is maintained energized when said circuit breaker is closed, irrespective of the phase relations of said sources.

7. In combination, two A. C. sources, a circuit breaker interposed between said sources, means for closing a contact when said sources are in phase, a second means for closing a second contact when said sources are in phase, means controlled jointly by said contacts for closing said circuit breaker, means including a relay for supplying the two means controlling said contacts with current from both of said sources, means whereby opening of said circuit breaker energizes said relay, and means whereby one of said means controlling one of said contacts is supplied with current from one of said sources only, when said circuit breaker is closed.

8. In combination, two A. C. sources, a circuit breaker interposed between said sources, a pair of means for closing two contacts respectively in response to predetermined electrical relations between said sources, means controlled jointly by said contacts for closing said circuit breaker, means controlled by said circuit breaker for supplying both of the means for controlling said contacts with current from both of said sources, and means whereby one of said means controlling one of said contacts is supplied with current from one of said sources only, when said circuit breaker is closed.

9. In combination, two A. C. sources, a circuit breaker interposed between said sources, a pair of means for closing two contacts respectively in response to predetermined electrical relations between said sources, means controlled jointly by said contacts for closing said circuit breaker, means controlled by said circuit breaker for supplying both of the means for controlling said contacts with current from both of said sources, means whereby one of said means controlling one of said contacts is supplied with current from one of said sources only, when said circuit breaker is closed, and means whereby when said circuit breaker is closed said relay will be energized irrespective of the phase relations of said sources.

10. An automatic synchronizing system comprising in combination, two lines energized with alternating E. M. F.s of independent frequencies, a switch for interconnecting said lines, a transformer energized from each of said lines, a relay connected in series with both of said transformers and having contacts, a synchronously operable motor energized from each of said transformers, cooperating contacts driven by each of said motors, and means responsive to the closure of said relay contacts and the subsequent closure of said motor driven contacts while said relay contacts are closed for actuating said switch.

11. An automatic synchronizing system comprising in combination, two lines energized with alternating E. M. F.s of independent frequencies, a switch for interconnecting said lines, two transformers connected to said lines respectively, a relay connected in series with the secondary windings of said transformers, two synchronously operable motors connected to the secondary windings of said transformers respectively, a plurality of contacts driven by one of said motors at a speed equal to that of said motor, a single contact driven by the other of said motors at a speed equal to that of said other of said motors, and means responsive to the contemporaneous actuation of said relay and engagement of said single contact with one of said plurality of contacts for actuating said switch.

12. An automatic synchronizing system comprising in combination, two inde endent lines energized with alternating E. F.s. two transformers each energized from one of said lines, a delayed action relay so serially energized from both of said transformers that its contacts are actuated in response to approximate phase and E. M. F. equality as between said lines, two synchronously operating motors connected to said transformers respectively, mutually cooperative contacts so directly driven by said motors respectively that said contacts are closed at substantially exact equality of phase and frequency, an electromagnetic switch, and means responsive to the actuation of said relay and the subseuent closure of said mutually cooperative contacts for causing the actuation of said electromagnetic switch.

13. In a synchronizing system, the combination of two lines energized with alternating E. M. F.s of independent frequencies, two transformers each energized from one of said lines, a switch, a control circuit for said switch, a retarded relay having contacts in said control circuit and having an operating winding connected in series with the secondary windings of said transformers, means for causing said relay contacts to partially completesziid control circuit a predetermined time afterthe vector sum of the secondary E. M. F.s of said transformers is below a pre-. determined value, .two synchronous motors "energized by said transformers respectively,

mutually cooperative contacts driven by said motors and'arranged to completeszud con trol circuit inresponse to phase and frequency 7 equality of said line EVM. F.s

In testimony whereof, the sinttture of the inventor is afiixed hereto. r

- PAUL M. STIVENDElfl so i 

